George a



G. A. THORNTON.

METHOD AND APPARATUS FOR MARKING METAL.

APPLICATION FILED 056.18, 1911.

1,309, 160. I Patented July 8, 1919.

UNITED sTATEs PATENT OFFICE- GEORGE A. THORNTON, OF CLEVELAND, OHIO,ASSIGNOR TO ADAMS-BAGNALL ELECTRIC COMPANY, OF CLEVELAND, OHIO, ACORPORATION.

METHOD AND APPARATUS FOR MARKING METAL.

Specification of iLetters Patent.

Patented July 8, 1919.

Application filed December 18, 1917. Serial No. 207,769.

Cleveland, in the county of Cuyahoga and- State of Ohio, have inventedcertain new and useful Improvements in Methods and Apparatus for MarkingMetal, of which the following is a specification.

This invention relates to the method and apparatus for marking metal byelectricity, the object of the invention being to provide a method andapparatus for printing or writing or branding metal by marking the sameelectrically.

In the drawings accompanying and forming a part of this specificationFigure 1 illustrates a form of apparatus which may be used to carry outthis improved method, this figure illustrating a piece of thick metalbeing marked by electricity and connected with a transformer. Fig. 2illustrates this improved method when used in connection with a thinmetal plate connected with the same transformer Fig. 3 is a perspectiveview of the apparatus as it is built for commercial use.

Similar characters of reference illustrate the same parts in the severalfigures of the drawings.

This improved method is particularly adapted for printing, writing orbranding tools and ot er articles of iron or steel. Heretofore in orderto brand tools or pieces of metal workit has been necessary to coat thearticle with asphalt, aint or wax to protect all those portions 0 thearticles that were not to be etched, then etch the article, then applyan acid thereto to eat away the etched ortion of the article, then cleanoff the aci and then clean oil the wax or asphalt used to protect thework around the etched portion thereof. Aside from the length of timerequired to etch in this way the results were unsatisfactory because ofthe resultant rust, acid marks and smudgy work. By the presentimprovement tools and metal articles may bemarked in about onefifth thetime heretofore required, the work left clean, as there is no cleaningrequired after the marking is finished elther of an acid or a protectivecoat ofasphalt or wax. Not only this but any desired style or size ofletters or fi res or designs maybe written, printed or randed upon themetal.

The use of electricity however for marking has not heretofore been foundpracticable for various reasons among others that it was not foundpossible to obtain the desired voltage for various qualities orthicknesses of metal or to steady the current to enable the article tobe properly marked.

In carrying out this improved method I provide a transformer 2, a metalplate 3 such as a copper plate suitably connected to the transformeraccording to the quality and characterof the metal plate or article tobe marked and a marking tool formed of metal such as copper alsoconnected with the transformer 2. The transformer is connected to asuitable source of electricity having preferably an alternating current,as it has been found that an alternating current is more desirable thana direct current for the reason that the latter has a tendency to burnand cannot be as easily controlled as an alternating current although insome instances a direct current may be used. The transformer isefi'ective to give the proper voltage according to the thickness andquality of the plate and to steady such current to en- .able the plateto be properly marked. It has been found by experiment that in order tomark a thin piece of metal less voltage is required than is necessarywith a thicker piece of metal of the same grade and quality and havingthe same depth or type of mark or printing thereon.

In Fig. 2 a thin plate 5 .is illustrated as being marked. In thisinstance the marking tool 4 and the plate 3 upon which the metal plate 5is located are connected to a smaller section of the secondary coil 6 ofthe transformer 2 whereby a lower voltage is obtained for use on theparticular thickness of plate shown. In Fig. 1 a thicker metal plate isillustrated as being marked and in this instance the plate 3 and markingtool 4 are connected with both ends of the sec ondary coil of thetransformer so that a higher voltageis obtained as is necessary in viewof the greater thickness of the plate.

In practice if desired the plate 3 could be dispensed with and thearticle to be etched be directly connected with the transformer but thepresent form of apparatus is more practicable since it permits any ageto be obtained from the source of electricity byreducing the voltage tothe required amount, according to the article to be marked, whileincreasing the current and steadying the same to obtain a uniformmarking. In other words the use of the transforn'ler enables the voltageto be reduced sufliciently low to produce a heavy current and steady thesame.

In Fig. 3 the apparatus as it is commercially used is illustrated, thesource of electricity in this instance being an alternating currentlight socket to which the apparatus may be readily connected ordisconnected as occasion requires.

By the present improvement steel and similar metal may be markedpractically as fast as writing with a pen, no acid or waxes are used,there are no parts to wear out except the copper marking tool or pencilwhich may be readily replaced with ordinary copper wire, so that withoutthe use of an etching acid or a protecting asphalt, paint or wax allthat is necessary by means of the present improvement is to write uponthe article to be marked in the ordinary way of using a pencil or pen.

In the present improvement, the mark- ;ing of the iron or steel plate oranalogous 30.

article is obtained by maintaining the pencil or marking tool in closecontact with the article to be marked, thus maintaining a closed circuitduring the marking of the article, the marking of the article being dueto the proper resistance established at the point of the marking tooland not bythe formation of an arc, such as is used for the cutting ofmetal.

In marking steel and a like material, by electricity as used byapplicant, the markingis caused by a current passing through thematerial to be marked and producing a burning temperature at the pointof contact rather than a series of minute arcs. This burning causes amark by eating away the material slightly and is done fast enough so asnot to affect the metal which is not at the point of contact. Naturallythe material whichis marked has the higher resistance to the electricalcurrent andis heated higher than the pencil which in the case of theapplicant, is a material of high conductivity.

I claim as my invention:

1. The method of electrically marking upon a steel or iron article whichconsists in providing a conducting medium and connecting the sametogether with the article to be marked to a suitable source ofelectricity through the medium of steadying means and then marking thearticle by the conducting medium while maintaining a close contacttherewith.

2. The method of electrically marking upon a steel or iron article whichconsists in providing a conducting medium and con- .source ofelectricity b necting the same together with the article to marked to asuitable source of electricity through the medium of steadying means,which steadying means is also effective to provide the proper voltagefor the article to be marked, and then marking the article by theconducting medium while maintaining a close contact therewith.

3. The method of electrically marking upon a steel or iron article whichconsists in providing a conductin medium connected together with theartic e to be marked to a suitable source of electricity through a meansfor reducing the voltage and steadying the current and then markino thearticle by the conducting medium while maintaining a close contacttherewith.

l. The method of electrically marking upon a steel or iron article whichconsists in providing a. conductin medium connected together with theartic e to be marked to a suitable source of electricity by means of atransformer effective to reduce the voltage and steady the current, andthen marking the article by the conducting medium while maintaining aclose contact therewith.

5. The method of electrically marking upon a steel or iron article whichconsists in providing a conducting medium and a supporting metal plate,the conducting medium and plate bein connected to a suitable source ofelectricity y means of a transformer effective to reduce the voltage andsteady the current, then placing the article to be marked upon the metalplate and then marking the article by the conducting medium whilemaintaining the conducting medium in close contact with the article.

6. The method of electrically marking upon a steel or iron article whichconsists in providing a conducting medium and a supporting metal plate,the conducting medium and plate being connected to a suitable means of atransformer effective to re uce the voltage and steady the current, theconnection of the supporting plate and conducting medium with thesecondary coil of the transformer being determined by the thickness andqualit of the article to be marked and then mar ring the article by theconducting medium while maintaining the conducting medium in closecontact with the article.

7. An apparatus for electrically marking upon a steel or iron article,comprising a transformer and a metal pencil, the pencil and the articleto be marked being electri- -ca1ly connected with a suitable source ofelectricity through the medium of a transformer.

8. An apparatus for electrically marking a steel or iron-article,comprising a transformer, a conducting pencil, and a supportingconducting plate for the article to be marked, the pencil and the platebeing 0100- trically connected to a source of electrical energy througha transformer.

9. n apparatus for electrically marking upon a steel or iron article,comprising a transformer and a metal pencil, the pencil and the articleto be marked being electrically connected with a suitable source ofelectricity through the medium of a transformer, the connections withthe secondary coil of the transformer being determinedby the thicknessand quality of the article to be etched.

10. An apparatus for electrically marking.

a steel or iron article, comprising a trans former, a conducting penciland a supporting conducting plate for the article to be marked, thepencil and the plate'being electrically connected to a source ofelectrical energy through a transformer, the connections with thesecondary coil of the transformer being determined by the thickness andquality of the article to be marked.

11. The method of electrically marking a steel or iron article whichconsists in connecting the article to be marked by a conducting mediumwith a heavy electric current oflow voltage transmitted through atransformer and then using said conducting medium to mark upon thearticle to be marked while maintaining the conducting medium in closecontact with the article.

12. The method of electrically marking a steel or, iron article Whichconsists in providing a transformer effective to reduce the voltage lowenough so as to produce a heavy and steady current and utilizin theterminals of the low voltage side 0% the transformer as electrodes onethereof forming the pencil for markin the article while maintaining theconducting medium in close contact with the article.

18. The method of electrically marking a steel or iron article whichconsists in providing a transformer having its primary terminalsconnected WlllhSJl alternating cur rent supply and having its secondaryterminals connected one With a marking penoil and the other With thearticle to be marked and then, by means of the pencil, marking upon thearticle While maintaining the conducting medium in close contact withthe article.

Signed at Cleveland, county "of Cuyahoga,

